Field of the Invention
The present invention relates to a printing system including a printing apparatus and a printing control apparatus of which the power state changes in association with the power state of the printing apparatus.
Description of the Related Art
A known printing system includes a printing control apparatus for receiving a print job from an external apparatus and generating raster image data according to the print job, and a printing apparatus for performing printing by using the raster image data received from the printing control apparatus (refer to Japanese Patent Application Laid-Open No. 2003-72198).
The printing apparatus discussed in Japanese Patent Application Laid-Open No. 2003-72198 includes a video interface circuit for receiving the raster image data transmitted from the printing control apparatus, and a network (N/W) interface circuit for receiving control information transmitted from the printing control apparatus. The above-described control information includes, for example, commands for performing printing by using raster image data.
The printing apparatus enters a power saving state when a certain condition is satisfied, for example, when the printing apparatus has not been operated for a predetermined time period. In the power saving state, the power supply to the N/W interface circuit is maintained but the power supply to the video interface circuit is suspended to reduce power consumption of an image forming apparatus.
As discussed in Japanese Patent Application Laid-Open No. 2003-72198, various power saving techniques for the printing apparatus have conventionally been proposed. Further, with the trend for energy saving in recent years, demands for power saving measures on printing apparatuses are increasing. In Europe, for example, energy-using products need to conform to the “EU Directive on Eco-Design of Energy-using Products (EuP Directive)” Lot 6 standard. To satisfy the Lot 6 standard, when no operation is made to a product for a predetermined time period, the product needs to automatically enter a state where power consumption is 0.5 w or below.
To achieve the state where power consumption is 0.5 w or below, a known technique causes a printing apparatus to enter a suspend state or a hibernation state. The suspend state is a state where the power supply to the main memory of the printing apparatus is maintained but the power supply to units other than the main memory is suspended. When the printing apparatus recovers from the suspend state, the printing apparatus can utilize working statuses stored in the main memory. Therefore, the printing apparatus can start more quickly than in normal start where applications and an operating system (OS) are activated. The hibernation state is a state where working statuses on the main memory of the printing apparatus are copied to a hard disk drive and the power supply to each unit (including the hard disk drive) of the printing apparatus is suspended. When the printing apparatus recovers from the hibernation state, the printing apparatus can utilize working statuses stored in the hard disk drive. Therefore, the printing apparatus can start more quickly than in normal start where applications and an OS are activated. The hibernation state suspends the power supply even to the main memory and therefore provides smaller power consumption than the suspend state. However, the hibernation state necessitates reading working statuses copied to the hard disk drive and therefore provides slower start than the suspend state.
In recent years, to achieve power saving for the entire printing system, power saving measures for the printing control apparatus have been taken in addition to the above-described power saving measures for the printing apparatus.